Joset A. Etzel , Erica L. Johnsen ,
Julie A. Dickerson , Ralph Adolphs 
 Iowa State University
 University of Iowa
This software was first described in: Etzel JA, Johnsen EL, Dickerson JA, Adolphs R. A program to accurately identify peaks in respiration and EKG signals for use in psychophysiological research. Psychophysiology 41 (s1), S73 (2004).
Please cite the above publication when referencing this material, and also include the standard citation for PhysioNet:
Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, Mietus JE, Moody GB, Peng C-K, Stanley HE. PhysioBank, PhysioToolkit, and PhysioNet: Components of a New Research Resource for Complex Physiologic Signals. Circulation 101(23):e215-e220 [Circulation Electronic Pages; http://circ.ahajournals.org/content/101/23/e215.full]; 2000 (June 13).
puka calculates descriptive statistics such as heart rate variability (HRV), peak-valley respiratory sinus arrhythmia (RSA), and respiratory variables from EKG and strain gauge respiration data.
Puka is a Hawaiian word meaning appear, emerge, or an opening, and is also the name of a small round shell with a center hole found on some Hawaiian beaches. It was selected to reflect the exploratory nature of the experiments which generate the data to be analyzed with this program as well as the new knowledge that may be gained.
puka, written in Java, uses MATLAB for signal processing and statistical calculations, and the WFDB Software Package and ecgpuwave for EKG peak detection. Puka can also read and write data from a MySQL database. puka was developed and tested using Cygwin under MS-Windows, but puka should be usable on other platforms supported by MATLAB as well.
puka incorporates a new method of identifying the breaths and pauses in strain gauge belt recordings. This technique locates the points of maximum inspiration and expiration for each breath as well as post-inspiratory and post-expiratory pauses. The authors found that puka correctly locates normal R waves in EKG signals and breaths in strain gauge belt recordings, in tests using artificial EKG data, paced respiration recordings from healthy young subjects, and recordings from neurological patients.
Sources and documentation for puka are available here.